APPEARANCES OF CULTURES. 



323 



is no liquefaction of the medium, and no formation of gas. 

 In stroke cultures there is a thin bluish-white film, but it 

 does not spread to such an extent as in the case of the 

 surface growth of a stab culture (Fig. 87, B). In gelatine 

 plates also the superficial and deep colonies present corre- 



FIG. 87. 



A. Stab culture of the typhoid bacillus in gelatine, five days' growth. 

 K. Stroke culture of the typhoid bacillus on gelatine, six days' growth. 

 C. Stab culture of the bacillus coli in gelatine, nine days' growth ; the gelatine is 

 split in its lower part owing to the formation of gas. 



spending differences. The former are delicate semi-trans- 

 parent films, with wavy margin, and are much larger than 

 the colonies in the substance, which appear as small round 

 points. These appearances, which are well seen on the 

 third or fourth day, resemble those seen in agar plates, as 

 already described in the method of isolation ; but on gela- 



